Problem with 940 stalling/cutting out

[GreenBrick]

I use engine oil as that does not cause any problems with 02 sensors, silicone based sprays would be a no-no I believe.

When I cleaned my IACV with the solvent it dried it out so much it wouldn't move until lubricated again. A bit like when I rinsed a gearbox out with petrol and found I could no longer turn it, until it was refilled with fluid.

[Laird Scooby]

Originally Posted by GreenBrick

I use engine oil as that does not cause any problems with 02 sensors, silicone based sprays would be a no-no I believe.

When I cleaned my IACV with the solvent it dried it out so much it wouldn't move until lubricated again. A bit like when I rinsed a gearbox out with petrol and found I could no longer turn it, until it was refilled with fluid.

Wise to be cautious but i doubt you'd get enough silicone lube through the engine to do anything to the Lambda sensor.

Something really doesn't sound right here - to need lubricating the mechanism would have to lose all of its oil/grease/lube and the mechanism isn't involved directly with the air flow, just the plunger/slide valve. That's the only bit that needs cleaning with carb cleaner and can be done easily without removing the valve, just the hose on the air filter side of the valve.

Just spray the plunger/slide valve with carb cleaner and job done - how does it get into the mechanism?

As an aside, i exhumed my can of carb cleaner today, removed the vac pipe from the inlet manifold, shoved the nozzle down the vac hose and gave it a good squirt until i heard it trickling down towards the oil filler cap. Tipped the hose a bit to help it get there and let it drip out before refitting the oil cap.
Did similar with the vac hose so when i refitted it to the manifold, carb cleaner ran down into the stub to clean it out.
Then i disconnected the MAF at the air filter and squirted a load more into it to clean the sensing wire.

When i started the engine, the EICV was working nicely as it brought the idle speed up a bit more than usual when cold. Think tomorrow when my new CPS arrives and i fit that, i'll re-clean the EICV while i have the tools out.

[GreenBrick]

On my 940, the IAC mechanism is a rotating valve that can get crap on its mating surfaces, so a good clean gets the muck out, but then leaves the mating surfaces so dry they don't slide nicely, so a bit of lube gets the surfaces sliding again.

[TomSaintJames]

Sorry to thread hi-jack, but this sounds a little like what my 740 does when started from cold, it often stalls or at best runs roughly until slightly warm. It is a mechanical injection, so no MAF/lambda etc. Would I have an IACV to check?

I have planned on putting some meths in anyway (not gotten around to it yet) as the car has done very few miles in the last couple of years.

[classicswede]

The idle valve is not the side. It is the unit mounted to the rocker cover. It operates on a bimetalic strip to open and close with heat.

It is possible to valve is not working right. More common is air leaks or a build up of oil and gunk in the air metering unit.

[Laird Scooby]

Originally Posted by TomSaintJames

Sorry to thread hi-jack, but this sounds a little like what my 740 does when started from cold, it often stalls or at best runs roughly until slightly warm. It is a mechanical injection, so no MAF/lambda etc. Would I have an IACV to check?

I have planned on putting some meths in anyway (not gotten around to it yet) as the car has done very few miles in the last couple of years.

No, you've got an AAV - Auxiliary Air Valve Tom and as Dai rightly says, it's mounted on the rocker cover. Inside it has a bi-metallic strip that bends or straightens according to temperature. On one end of the strip is a slide valve, on the other end which is mechanically fixed inside the body of the valve, is a heating coil fed by an ignition switched feed.
With the ignition on, the coil heats up, bending the strip and moving the slide valve into the closed position.

Best method i found of cleaning them is to pull the hoses off each side and spray carb cleaner in, after it's been for a run so the valve is definitely closed.
Let it cool down and give it another good squirt each side, check it's opened up, refit the hoses and start the engine. It should idle slightly higher than previously but more importantly, a lot smoother.

There are other faults in the K-Jet system that can occur that will cause rough running when cold but this is the main one.

[TomSaintJames]

Thanks chaps, will investigate.